AxleSchmaxle

Hi all Just had a phone call from my fiancé saying that my lupo 1.4 wasn’t revving above idle; apparently it was revving 100 rpm above idle and not going any further but sounding like it was misfiring or spluttering. I jokingly said “have you tried turning it off and on” and it worked, after starting it again it would rev all the way to redline again anyone have any idea what could’ve caused this to happen, and more importantly why turning it off and on again fixed the issue?